Our starting point is the expression of the SGF in terms of the group integral similar to (REF ) [1]}
\({\mathcal {S}}(\lbrace z_l,\tilde{z}_l\rbrace )=\sum _{j_1\cdots j_6} \left(\prod _{n=1}^4(J_n+1)! \int _{\mathrm {SU}(2)}\mathrm {d}h_n \right)\prod _{l=1}^6 \frac{1}{(2j_l)!}\left[ j_l, \tilde{z}_l \right| h_{t(l)}^{-1}h_{s(l)}\left|j_l,z_l \right>\) 
